Optical devices, the optical state of which can be varied when supplied with electricity, have been proposed. For example, Patent Literature (PTL) 1 discloses a light-adjusting element that includes an electrolyte layer including an electrochromic material containing silver between a pair of transparent electrodes; and the pair of transparent electrodes between which the electrolyte layer is interposed and one of which includes nanoscale peaks and valleys. The light-adjusting element in PTL 1 can form a mirror state through the application of a voltage.